Well cementing apparatus



Dai. 29, 1953 Filed April 16, 1949 s. B. scHNn'Tr-:R

WELL CEMENTING APPARATUS 3 Sheets-Sheet 1 73 fig., I

IN VEN TOR.

ATTORNEY Dec. 29, 1953 s, B SCHNlTTER 2,664,163

WELL CEMENTING APPARATUS Filed April 16, 1949 3 Sheets-Sheet 2 Sy/ve ster Schn/'Hef- INVENTOR.

A TTORNE Y De@ 29 1953 s. B. scHNlT-rER WELL CEMBNTING APPARATUS I5 Sheets-Sheet I5 Filed April 16, 1949 .5y/veder B. Schm'tter INVENTOR. v/QW ATTORNEY Vstructures of the said plugs.

Patented Dec. 29, 1953 WELL CEMENTIN G APPARATUS Sylvester B. Schnitten', Dallas, Tex., assignor to Y L. L. Rector, Tarrant County, Tex.

Application April 16, 1949, Serial No. 88,020

8 Claims.

This application concerns improvements in apparatus for cementing casing to strata in a well bore; and particularly concerns improvements in the segregation of fluids in a well casingv for the purpose of maintaining the homogeneity and uncontaminated state of such fluids used during a well cementing operation.

The essential purpose in discharging a cementitious slurry material free of contamination from casing into a well bore behind the casing is to seal off selected sub-surface strata. The uncontaminated slurry bonds the casing to the said strata which are thus blocked to prevent intercommunication of migrate uids vertically 'along the casing.

The failures to obtain successful results when bonding casing to Well bore strata are due to the intercommunicating action of fluids during channeling, consists of the mingling inltration of a slurry into or from a typical Well mud during the time the slurry is moved in the well casing. Obviously, a contaminated slurry mass, incapable of forming a true set behind a casing, constitutes a region oi weaknessin the well bore and permits migration of strata fluids past the intended cementing bond.

More than one nuid is pumped in the ow circuit during a cementing operation. These `fluids are divergent ones, differing in character l and properties. Normally a slurry is heavier in fluid weight than the typical Well mud displaced, though it is not unusual to have the said well mud heavier than the slurry. t t

As a result of the varied resistances of ordinary well iiuids to flow motion, and which said provided sealing and pliant cementing plugs of resilient material to prevent the intercommunication of the said fluids through or about the My cementing plugs suitably establish and maintain dened movement of the said iiuids therein. and is especially adapted for use with my cementing method and apparatus disclosed in my co-pending apition Serial No. 757,452, filed on June 27,

YIn former cementing practices, there are disclosed several forms of conventional spacer plugs intended to segregate the portions of slurries from the well muds to prevent free contacting fluid interfaces incasing bores.` These said cementing plugs have flexible and slideable Wipers or slideable and yieldable limiting sealing members, easily flexed in collapsed movement, which permit the bypass and intermixing of iiuids.

A former conventional primary or bottom plug, and a former conventional top plug, used collectively to segregate a slurry from thewell mud, cooperated to createy slurry contamination. That is to say, a heavier slurry waspermitted to by-pass about a conventional primary plug into a lighter well mud below, and a similar said heavier slurry was permitted to by-pass labout a conventional top plug` into a lighter Wellmud y above; also, a heavier well mud was permitted to by-pass about a conventional primary plug into a lightery slurry above, and a similar said heavier mud was permitted to by-pass about a conventional top plug into a lighter slurry below. My cementing plug supplies positive segregation when spacing iiuids. It is made from natural or synthetic rubber or the like. They are thus sealingly pliant and have a resilience or energy of positive response in fast comeback after deforming and releasing. y

The properties. of the resilient stock from which my plugs are made, after vulcanization, tend to approach thoseof completely elastic material. When subjected to shearing stresses, such stocks will now in elongation and distortion, and are capable of quickly recovering their original shape by virtue of elasticity. f

- My plugs are used kfor the primary plug and also for the top plug inr cementing operations.

When used as a primary plug it is pressured for movement in a casing bore. This pressure is supplied from the pumps during and after 4the introductionof` the primary plug into the is the heavier fluid in the cementing circuit, the

said slurry exerts the force of pressure on my Aprimary plugs after their introduction into the cementing circuit. v Y

The said forces exerted penetrate into the interstices of my primary plugl'ocated on the up- 3 per side, and is confined therein above the baffle by the areas defined by the upper webs, inner cylinder and sealing face. Since a pressure acts equally at the interfaces of two fluids in motion, and since rubber acts like a fluid, a substantially similar pressure is present below my segregating primary plug. The said pressure, therefore, is ypenetrably presentwithin the lower interstices .of my primary plug below the baffle and is conned therein by the areas defined by the lower webs, inner cylinder and sealing face, and also by the hollow bore of my primary plug.

The sealing faces of my cementing plugs do no possess slideable wipers or easily flexing and.V

collapsing limited seals when segregating fluids in a casing bore. My cementing plugs are oversize for the casing bores wherein they are used, and they have elongated and continuing sealing faces.

My cementing heedis a novel arrangement which provides the-orderly pressured induction of my cementing plugs into a casing bore. My cementing plugs are made oversize, to` possess frictional contact to the walls of casing bores. My plugs, therefore, must be deformed to lesser sizes than casing bore sizes in order to acquire their saidfrictional contacts within the casing bores.

My cementing head has a bore di: meter greater than the casing bore diameter to permit the easy ejected from the plug to permit quantitative fluid Y discharge from the b'ore of the plug. The contour i of the plug. thereby reduced, is then elasticrlly reformed when entering the casing bore, which reforming is assisted by fluid return to the bore ofthe plug. This action of'fluid return to the plug bore is resultant from the force of suction created within the bore of the plug by the said previous fluid discharge from the plug under submergence.

My p lug-l is `soconstructed with a hollow bore and-spaced interstices around the ends thereof thatit may be easily deformed and reformed but at the same time is provided with stability when submerged under pressure.

My cementing plugs are inserted in the cementing head prior to attaching the cementing head tothe casing string. This inserting of plugs is donev at the derrick floor where easy access to the bore.of the cementing head is available to arrange their order. Releasrble members retain the fixedV positions of the plugs in the cementing head untill the -p'lugs are freed in sequenced order for proper pressuredpositioning in the casing bore.

Thus my,plugs are arrayed in the casing bore whereby aprecedingpor primary plug is placed below the Yinitial portions of a slurry charge and a top plug is placed above theiinal portions of the. said slurry.

Myplugma-y also-be used -to segregate a dispersing fluid from the ordinary fluids when desired. In fact it may be used to segregate all fluids used in a cementing operation.

Among the objects to be accomplished by my invention, in addition to the foregoing, may be found the following:

1, The provision of a new type of fluid Segregating plug to be used in the segregation of fluids in a conduit, which plug is made of pliant and elastically retractable material so that it may be deformed by pressure and reformed by elastic recovery action when pressure is relieved or partially relieved therefrom.

2. The provision of such a plug made of larger diameter than the casing through which it is l, intended to pass, the plug being contracted for admission into the casing so that the outer side thereof will have tight frictional engagement with the inner walls of the casing through which it passes.

3, The provision of such a plug with an elongated outer fr ce thereon which provides for additional surface for contact withthe inner walls of the casing to prevent fluid from by-passing around the plug from above and below same.

4. The provision of such a plug with anelongated outer face thereon and a-n upper lipr and a lower lip around the upper and lower side thereof, which lips are extended outward from theouter face of the plug, and provided sothat when the plug is contracted by pressured movement through the well pipe the saidlipswillbe elongated rnd brought in the sanevplanewith the outer face of the plug so thata tight frictional engagement will be brought about betweenrthe outer walls of the plug and the-inner surface of the well pipe, and to alsoA compensate for'frictional wear on the outersurfaceVV of the plug as it is moved by pressure through the well pipe.-

5 The provision of such a plugiwith e. series-of spaced interstices around each end thereof, said interstices being separated'bya series of webs forming walls thereof, and the interstices at the upper and lov-.ferfedges thereof'having a common bottom defined by a baille.

6, The provision of such'a'plughaving:` 4hollow interior closed at one endr bya connector member so that the plug mayy be-connected-to another member and thus convey itthrough the well pipe, and said hollowinterioribeing openat its other end and adapted to be-closed by" a stopper or other suitable closure member.

'7, The provision of a modifiedformfof such plug in which there are a series oi?` peripheral skirts around the upper and-lowerends thereof connected together by a series of web members, such skirts and web rrembers forming aseriesof spaced interstices about the upper and--lowerends of the plug, said intersticeshaving a common bottom defined by a bale.

a, The provision of a special cementinghead for use with the aforescidA plug-Which head is adapted to be attached tothe upper/end vof a string of casing, and hasancinner'diameter at the place of joinder between the `head land the casing of lesser diameter thanthe interior diemfrom the said hollow bore `sothat when Athevplug passes the constriction fluid 'will be sucked back into the hollow portion by force of vacuum.

Other and further objects of my invention will become apparent by referring to the drawings and reading the detailed specification which follows hereinafter. n

Preferred embodiments of my invention are shown in the drawings attached hereto, in which drawings:

Fig. I is a side elevational View of a string of well casing with my specialized head attached to the upper end thereof, and with a, float shoe attached to the lower end thereof, and having ra stall collar intermediate the upper and lower ends thereof.

Fig. II is a side elevational view, partially sectionalized, of the preferred form of my new type fluid spacer plug.

Fig. III is a side elevational view, partially sectionalized, of a modified form of my fluid spacer plug.

Fig. IV is a side elevational view, partially sectionalized, of my specialized cementing head used with my new type plug, and showing the trip ball, primary plug, top plug and back pressure check valve releasably positioned therein, ready to start a cementing operation.

Fig. V is a cross sectional view taken along the line V-V of Fig, IV.

Fig. VI is a cross sectional view taken along the line VI-VI of Fig. IV.

Fig. VII is a fragmentary, cross sectional elevation of the upper part of the back flow check valve, cap for the cementing head, and the handle for holding, and releasing the back flow check valve in the head.

Fig. VIII is a fragmentary cross sectional elevation showing the channel on the outer side of the cementing head with the communications between same and the cementing head, provided to equalize the pressure in the cementing head above and below the top plug.

Fig. IX is a fragmentary, side elevational view, partially sectionalized, of a string of well casing with my float shoe attached to the lower end thereof and the stall collar spaced above same.

Fig. X is a fragmentary side elevational View, partially sectionalized, of a string of well pipe showing the frangi'ble float assembly having been expelled from the casing and the primary plug and the top plug, with the back flow check Valve attached thereto, spacing a quantity of cementing slurry in the well pipe.

Fig. XI is a fragmentary, side elevational view, partially sectionalized, of a string ofcasing showing the, frangible float assembly having been expelled by the trip ball into the bore of the well, and the primary plug having been expelled into the bore of the well, and the back flow check valve having been guided and locked in place in the stall collar, and the cementing job having been completed by expelling the cement to the space between the well pipe and the outer walls of the well bore.

In the drawings, numeral references are used to designate the various parts thereof, and like numerals are used to designate like parts, and in which numeral I indicates a string of conventional well casing used in a well. Attached to the lower end of the well casing is a float shoe 2 of a specialized type used in my method of cementing oil wells as disclosed in my co-pending application for United States Letters Patent, Serial No. 757,452 led on June 27, 1947.

Stall collar 3 is positioned intermediate-the 6: edsofthe' lcasing I'Lat a desired place'. 4 indi-J cates a casing coupling in which the stall collar is screwed. At the upper end of the well pipe is positioned the cementing head 5, which yis secured to the well casing by means of the collar 6.

The upper end of the cementing head 5 is closed byv a cap 1 which is threaded into the top of the cementing head. A handle 8 is provided with a shaft passing through the cap 1 for the purpose of releasing the back pressure check valve into the well ow circuit, in the manner which will 'be hereinafter described in detail. The shaft for'the handle 8 passes through the housing 9 and through the cap 1. The housing 9 is secured to the top of the cap 1 and has two oppositely disposed extensions thereof, which are for the purpose of limiting the rotation of the handle 8, for the purposes and in the manner which will be hereinafter described.

Positioned on the outer periphery of the ceinenting head 5 is a channel member IIJ, which is provided with communication at the upper and lower` ends thereof with the interior of the cementing head 5 so that pressure may be equalized above and below the top cementing plug when positioned in the head 5. This will also be described in more detail later.

The handle II may be seen on the outer side of the cementing head 5 in Fig. I, which handle is provided for the purpose of releasing the primary plug into the well flow circuit at the proper time. A trip ball receptacle I2 is provided on the outer periphery of the cementing head and has a handle I3 passing therein for the purpose of releasing the trip ball into the cementing circuit. The detailed function and operation of this mechanism will be described hereinafter.

A flow line I4 communicates with the cement mixing unit (not shown)v and causes communication between such unit and the cementing head through the valved inlets to such cementing head;

and the flow line I5 communicates with the well, pump and permits the pumping of well mud;

from surface storage facilities into the cement-- ing head through the selected valved conduit leading into the hea-d. These valved conduits I5, I'! and I8 communicate-with each other through the connecting pipes I9 and 20. A selected flow of fluid may be admitted into the casing by mere manipulation of valves on the conduits I5, I? and I8. yThe flow lines I4 and I5 are connected to the pipes I9 and 29 and communicate with the valved conduit IS, II and I8 through the cross connections 2|.

Figs. IV, V, VI, VII andk VIII show the detailed construction of the specialized cementing head used with my new plug and intended for use with my "full bore cementing method as di"- closed in my co-pending application, referred to above. In these gures passage 22 connects with the valved inlet I8 by being threaded thereto through a suitable collar, and well huid is admitted therethrough into the cementing head and pumped through the well flow circuit before the cement is admitted into the well ow circuit, for the purpose of determining whether or not there is a free ilow of fluids through the well liow circuit. This conduit may also be connected to facilities for admitting a dispersing fluid for the purpose of conditioning the well rmud'in the well now circuit, before admitting the cementing slurrythereto. y 1

The trip ball 23 kis shown positioned in the amarres bally receptacle I2: ready for releasing. into= the Well flowVv circuitY after.: or: during the: aforesaid circulation has-been completed; .for thepurpose of pumping thesame down :to position in the `'ira-ngible oat assembly" 95; toz-expelisamefrom the well pipe to permit a free ow of fluids through the well circuit duringlthe cementingopera-tion. This trip hall is vof conventional type', and :isf made of a Adrillable material.

The trip `ball receptacle z l 2 -rconstitixtesf -afcylim drical housing, which is':welded:topthe--outerfpe rphery of the cementingfheadt andthe outer end thereof is :interiorly 'threaded fto receive. .the threaded vplug 24;

The .plug I 24 has a central ybere orropening; 25 passing therethrough; which; bore;y is:- interiorly threaded .to receive .theiplug '2.6. Plug 2 Bffordinarb ly closes thepassage orf-bore 25;: butit may-be removed for thep urposesofmounting thereina pressure gauge, .which is usedato record the varying pressures duringa-well cement-ing operation.

The cylindrical'housing 21 is weldedl to-the outerperiphery-of lthe ball receptacle I2 `and is interiorly threaded at its outer'end tc receive the threaded 'stufIing-ib'ox `28.

The stuffing box` 2B: has a' packing elementJZQ at the inner end'thereof, around'the-shaftfor the handle I3, which packing Yelernent is recessed from theV` interior Wall of thexballreceptacle/I2 so that the head 32;..0n theinnerxend of the Y handle I3, willenterr-said recessnand will'not protrude-into thetinterior-of the hail receptacle I2, when the handle I3 is pulled outward. The ball 23 is thusallov/ed to .freely vfall into the ce- Aenting heady 5 when' it is releasedby/Withdrawing the han'dlegl I.

The packing velement s29:is1 providcd'tc prevent mud and other lforeignzmatt'er from escaping from the ball receptacle i2 'into-the bore'.'

The bore 3D passes *centrally* through the .packing gland 28 and Vis providedY to 'admit the shaft of the handle I3 to pass through the packing gland 23 to the interior oftheball;receptacle. Another packing element 3| is provided .around the shaft for the handle I3 which packing element is spaced from the packing elementZil.

The head A32, onth'e inner end of the handle is of cylindrical shape and has a rounded outer surface which engages the ball 23 and holds it in the receptacle I2 until the .handle I3 is pulled outward toallow the ball to fall into the cementing head in. the manner which willbe hereinafter described. The head 32 is larger than the -bore passing through the packingZS, and the bore passing through the stuiling box-28 to prevent the handle I3 from beingpulled en-y tirely from the .ball receptacle I2.

The handle I3.is locked against Withdrawal from ball receptacl'eIZ, afterbeing pushed in. Ward to hold .the .balli in thereceptacle .I2,'by a jay slot arrangement which is exactly the same in construction as 4the jay slot arrangement used in connection with the handlerl I, which will be described in detail hereinafter.

The opening 33 is provided in the outer .shell of the cernenting head 5, which opening corn-- rnunicates With, and is'rconnectedto, thevvalved conduit I1, and is ordinarily usedtopadmit the cementing slurry intothe cementing head and therethrough into the casing by opening the valved conduit I1, after 'the primary plug 34 has been released in the manner hereinafter de scribed.'

The primary plug is hung in the cementing head by means --of fan-1 |.eye-'35,1' which eye is provided S with female threads: inll thev end of the shank thereof which receive the male threads on the connector. member 14 of the plug 34.

The'shaft36-of the` handle II passes through the' eye 35 andthe inner tapered, enlarged end 31 thereof is inserted through the hole 38 inthe side of the cementing head 5 and is received in the cylindrical'housing 39. The housing 39 is Welded to the outer side of the cernenting head 5 overfthe hole 38, thus receiving and supporting thehead 31 on the shaft 35.

The end 31 of' the'shaft 35 is enlarged and tapered outwardlyso that when shaft SS-is withdrawn infthe manner hereinafter described the head 31 will easily pass through the eye 35 and allow the'plug 34 to be released into the well flowV circuit but the head 31 is too large to permit the complete Withdrawal of the shaft 361 from the Ahead 5.v The shaft 36 is free to rou tate in the hole 33,' so that the handle Il may be rotated, in the manner which will hereinafter be described, to allow the withdrawal of the shaft 33" throughthe eye 3 Cylindrical housing 49 is welded to the outer side ofthe eementing head E'and forms a casing forthe stuiing box 4I.` Housing 43 is interiorly threaded on its outer end to threadedly receive theY stuffing box 4|. A central bore 52 passes through the stuffing box 4I and receives the shaft 3E'on theV handle II. The packing 43, which is recessed, from the inner Wall of the cementing head to admit the head 31 in such recess, is provided around the shaft 33 to prevent debris from leaving the cementing head through the 'bore 42. Another packing element 44 is provided around the shaft 36 to further prevent debris from leaving the cementing head through the bore-12.'

A horizontal slet 45 is provided in the stuiiing boxv 40;' which slot is formed by extending the bore 42outward to the outer periphery of the stuffing box 4i.

Another slot 46 is cut at right angle to the slot 45V and' connects therewith a slight di.n ance inward from the extreme end of the stuffing box 4I; This forms what is commonly known as a jay slot.

When itis. desired to. pull the shaft 36 of the handle II outward, in order to release the plug 34 'into the Well low circuit, the handle il, which' is .shown in Fig. IV as being pushed nward and resting in slot 445,Y is turned counterclockwise as is denoted by dotted lines in Fig. lV. The handle II will thus be made to register with .the horizontal slot 45. Thenthe handle II maybe-pulled backward, and the shaft 36 thoreon will slide Voutward through the bore 42. Thereby .the end-31, of the shaft 3G, is pulledvoutward through the eye and the plug 34 -is thus released into-the head E-and permitted to enter the Well casing.

When hanging the plug 34 in the cernenting head in the position shown in Fig. 1V, the shaft 3G isi-inserted through the eye- 35 and pushed inward, and-'the head 31 `is inserted through the hole 33 and into the 'receptacle 39. The handle I I is turned-clockwise when it cornes in register with-thelslot 45,- thus'locking it in place and preventingthe outward movement thereof until the handle Il is again turned counter-clockwise to-cause itto-niatch with the slot 45.

This "jayv"' slot-arrangement, described in detail above;I forflockingqthe Vhandle II against withdrawal lis 'eil'.actly Y'the -vsame 'in' construction as the jay slot arrangement provided for locking the handle I3 against withdrawal.

The passage 41 which is donned by a hollow cylindrical member Welded to the exterior of the cementing head 5, leads into, and communicates with, the interior of the cementing head and is connected with, and communicates with, 'valved conduit I5, through which well mud may be flowed into head 5 and therethrough into the casing, after releasing the topr plug 48 with the back pressure check valve 49 attached thereto.

Back pressure check valve 49 is provided. with a central bore in the bottom thereof with female threads therein (not shown) which are adapted to receive the male threaded connector mem`^er i4 provided on upper end of the plug 49. The plug 49 is connected with the back pressure check valve 49 so that they will travel together through the casing string, and the back pressure check valve 45 will be conveyed by plug 48 to a seated position in the stall collar 3.

Back pressure check valve 49 is provided with a spring loaded split ring' 59 which is adapted to he contracted into a recess on the body of the back pressure check valve 49 when force is applied to the outer periphery of the said ring. Such a force is applied to-said ring when the lower end of valve 49 is forced through the inner tube v5I in the stall collar 3. When pressure is released from the said ring, upon passing below the inner tube 5i, it will relax by spring action behind a shoulder on the lower side of the inner tube 5I. Y

The back pressure check valve is also provided with resilient packing rings 52, extending around the body thereof, which seal against the inner sides of the inner tube 5| when the back pressure check valve is locked in position in the stall collar 3.

A taper 53 is provided'on the upper end of the back pressure check valve 49 which mates with the inner taper or valve seat 54 in the upper end of the inner tube 5I, and stops the progress of the back pressure check valve in the casing when the said taper 53 is seated in the valve seat 54. Thus the pumps, which are circulating the fluid in the well circuit, are stalled, and the flow of :duide upwardly and downwardly in the casing string and behind the. casing, is immediately stopped, since the back pressure check valve 53 may not move downwardly, and it may not move upwardly by virtue of the split ring 59 being 'locked behind the shoulder on the lower side of `the inner tube 5|.'

The vertical slots 64 are cut on the opposite sides of the top of the valve member 49; and a horizontal slot 55 is cut at right angles to and communicates with eachslot 64. The slots 55 are cut in opposite directions.

The shaft 56, which has an upper enlarged portion to fit the 'housing 9, is attached to the handle 8 and rotatively extends through the housing 9 and through the cap 1, and is .provided with a tapered mating member 51 on the lower end thereof. Y

The top of the valve body 49 is provided centrally with a tapered bore 58, which is adapted to match, and rotatably receive the mating member 51. The mating member 51 has horizontally disposed pins 59 extending from the outer sides thereof; and the cap 1 has a pair of vertically disposed pins 50 disposed on the under side thereof and oppositely disposed to each other. Each of the pins 69 is adapted to nt into a slot 6l in the top 0i .the back pressure Check `valve 4.9.

When mounting the spacer plugs and back pressure check valve in the cementing head 5 the back pressure check valve 49, with top plug 48 attached thereto, is attached in locked position to the cap 1 before the cap 1 is placed in the top of the head. This is done by inserting the member 51 into the female mating member 58 in position so that the pins 60 on the bottom of the cap 1 will match with and be inserted in the slots 6| in the top of the back pressure check valve; and the horizontally disposed pins 59, on the mating member 51, are made to match with and are inserted in, the vertical slots 54. The handle 8 is then rotated counter-clockwise so that the pins 59 will enter the horizontal- 1y disposed slots 55.

A hole 62 is provided through the upper enlarged portion of shaft 56, and a hole (not shown) is provided through the housing 9, which hole is adapted to match with the hole 62 when the handle 8 is rotated counter-clockwise. When the holes are thus matched, the pin 63 may be inserted through the said holes, thus locking the shaft 56 and preventing it from rotation until the pin 63 is withdrawn to permit clockwise rotation, Thus'the top cementing plug, attached to the back pressure check valve, is locked in stationary position in the cementing head. The pins En, in aligned position in the slots 6|, prevent the rotation of the back pressure check valve 49 about its vertical axis. When the pin 63 is withdrawn and the handle 8 is rotated in a clockwise direction, the pins 59 also rotate clockwise in the horizontal slots 55 to match the'pins 59 with the vertical slots 64, and allow the back pressure check valve to be released from the cap 1.

vSuitable packing 65 is provided around the shaft 8 'Where'it passes through the cap 1.

The housing y9 is provided with extensions on the upper end thereof which are oppositely disposed and limit the rotation of the handle 8. The maximum rotation of handle 8 in counterclockwise direction supplies alignment to hole 62 through shaft 56 with the hole (not shown) in housing 9, and the maximum rotation of handle 8 in clockwise direction supplies alignment of pins 59 andthe vertical slots 54 of the back pressure check valve 49.

rlhe cap 1 has a skirt or extension 61 thereon which is provided with exterior threads on the lower side thereof and is secured in the cementing head 5 by threading Same into correspondingly matching female threads in the top of the cementing head 5. The skirt 61 is provided with a resilient packing 68 around the lower side thereof.

As described above, the back pressure check valve is locked in position on the under side of the cap 1 before the cap is screwed into the top of the cementing head. Then, when it is desired to release the back pressure check valve, with the plug 48 attached thereto, into the well cementing circuit, at the proper interval, it is only necessary to withdraw the pin-6 3, turn the handle r per end of said channel; and a hole |00 is provided through the outer wall of the cementing head near the lower end of said channel. Thus communication is provided between the upper and lower ends of the top plug 48 through channel i0, when said plug is positioned in the cementng head, for the purpose of equalizing whatever force is present inside the cementing head above and below the top plug at lall times, and allows the plug 48 to be held in equilibrium before being released into the well flow circuit.

The preferred form of my new cementing plug, which may be either the primary plug 34 or the top plug 48, is shown in detail in Fig. II.

This plug has a sealing face 69 thereon, which sealing face has a long continuing contact with the bore walls of the casing, by frictional engagement therewith, upon its movement through the casing bore. An outwardly diverging lip is provided on the upper outer vside of the plug and a lower outwardly diverging lip 1| is provided on the lower outer side of the plug. These lips 1U and 1| are not in the same plane with the sealing face 68, but are brought into the same plane therewith when pressure is applied to the plug and it is contracted and elongated in frictional engagement with the bore walls of the casing. After the plug is so contracted and elongated by pressure, the outer periphery of the plug, including the outer side of the sealing `face 69 and the outer sides of the lips 18 and 1|, form one continuous straight line in frictional engagement with the bore of the casing. These lips, 10 and 1|, are provided to assure `tight frictional engagement by the outer face of the plug with the inner bore of the casing, even though the outer face of the plug may vbe worn away by friction when forced through the casing bore.

The plug has a hollow 'bore 12 therein which is open at one end and is closed at the other end by the connector member 14. The open end of the bore 12 is adapted to be closed by a stopper 13 which may be made of any suitable material such as cork, aluminum, or any other drillable material. This stopper is inserted and held in the openingr to bore 12 by frictional engagement with the interior walls thereof.

The threaded joinder member 14, which is made of metal of a drillable nature, such as aluminum or the like, has a lower end portion 15 which is hour glass shaped, that is, the middle f' portion is less in diameter than the upper and lower portion thereof, and is tapered from the center outward toward both ends, and the outer periphery thereof has steps or waves therein. This lower end portion is molded into the -upper cylindrical extension 16 of the rubber plug at the time the plug is made and the shape thereof, with the upper and lower ends of larger diameter than the middle thereof, and with the steps thereon, prevent the connector member 14 from being pulled from the plug.

A baffle 11 is provided which extends continuously around the plug and the upper face thereof connects the inner surface 18 of the sealing face 69 and the upper cylindrical portion 16.

A series of spaced upper webs 19 are provided around the upper end of the plug. These upper webs connect the baille 11, cylindrical extension 16 and the inner face 18. It will be noted that the upper ends of the webs 19 do not come to 7 the outer end of the cylindrical member 18 and the lower ends thereof do not extend to the top of the inner side 18 of the outer face 69. There are a plurality of these webs 19 disposed at spaced intervals around the top of the plug, and these `:12 webs, together with the Vcylindrical member 16, the upper side ofthe lbaille 11 and the inner face 18 of the sealing face 69, dene a series of spaced interstices around the upper end of the plug.

The outer sides of the hollow interior 12 of the plug forms a lower cylindrical member 83. The inner side of the lower extension 82 of the sealing face 69 is connected to the lower cylindrical'member 83 by the lower side 8| of the baille 11.

A series of lower webs 84 are provided at spaced intervals around the lower end of the plug. These webs connect the outer surface of the cylindrical member 83, the lower edge 8| of the baille 11, and the inner side of the lower extension 82 of the sealing face 69. These webs 84, the baille 11, the inner surface 82 of the sealing face and the outer surface of the lower cylindrical member 83, deilne a series of spaced interstices 85 around the lower end of the plug.

This fluid spacer plug has the attribute and capability of being easily deformed when pressure is exerted thereagainst. At the same time, it has the attributes .of a solid when it is submerged in a non-compressible fluid, or nearly so non-compressible fluid, and pressure is exerted thereagainst. This is so because the hollow interior of the plug is filled with fluid and the interstices 80 and 85 are filled with fluid; and when the plug is deformed and elongated by pressure fluid is expelled from this hollow interior and the interstices; and when pressure is released therefrom the plug reforms and relaxes and fluid is drawn back into the interstices and the hollow interior by force of suction. The plug is maintained in a rigid state at all times while under pressure and moving in the well flow circuit during a cementing operation.

Frictional engagement with the bore walls of the casing is provided by the outer sealing face of the plug, and by the sealing lips thereon, when the plug is deformed and elongated by pressured movement through a bore of smaller diameter than the plug. This plug is made of larger diameter than the bore of the casing in which it is used and is thus elongated into frictional engagement with the bore walls of the casing as it moves in the bore.

Fluid is prevented from passing around the plug and none passes through it. The hollow bore and the interstices of the plug are filled with nuid While the plug is moving in a casing bore and separate and define two different columns of fluid therein.

The elongated, unbroken .and continuous outer Aface of the plug provides stability and keeps it from wobbling while moving through the casing bore. This capability is not found in any plug presently used in cementing operations.

The interstices of the upper and lower ends 40f the plug allow the plug to be more easily deformed and elongated for passage through a .casing bore of smaller diameter than the plug, or through a restricted area in the casing bore, while at the same time such interstices lend rigidity to the plug by confining within the plug the forces encountered by it.

A modified form of my cementing plug is shown in Fig. III wherein the outer sealing face 69 and the upper and lower lips 1D and 1| are the same in construction as in the preferred form hereinbefore described; and the upper cylindrical member 16 and connector member 14, with extension 15 thereon, and the hollow interior 12 are the same in construction as that described above in reference to the preferred form of my plug.

In this modified form a series of upper interstices 86 are formed about the top of the plug.

A plurality of upper peripheral skirts 81 extend outwardly from the baffle 88. A series of spaced upper webs 89 are positioned diagonally across the peripheral skirts 81 and connect them together. An upper interstice 86 is defined by the innermost peripheral skirt 81, tWo Webs 89, baiile 88, and the cylindrical member 16, and there are a series of these interstices around the periphery of the upper side of the plug adjacent to the cylindrical member 16. There are also a series of these interstices 86, extending around the upper end of the plug, each of which interstices is dened by oppositely disposed walls of two peripheral skirts, a web member 89 on each side thereof and the baie 88 forming the bottom thereof. The outer series of spaced interstices 86 around the upper end of the plug, are defined by a peripheral skirt 81, the inner side of the sealing face 69, two web members 89, and the baiile 88.

A plurality of lower cylindrical skirts 9i are positioned around the lower end of the plug which, with the web connecting members 92 and the baffle 88, form a plurality of lower interstices 96 around the lower end of the plug. These interstices are formed in the same manner as was described above in reference to the upper interstices.

This modiiied form of plug has the same function and advantages as the preferred form described above, in that it has a hollow bore, an elongated sealing face, and spaced interstices around the upper and lower ends thereof, with an expellable stopper member 13 to close the bore 12 therein. It is easily deformed and reformed and has the attributes of a solid when submerged under pressure.

The operation and function of my new type of fluid segregating plug with the special head designed therefor may be stated as follows:

Ordinarily the cementing head with the trip ball, primary plug and secondary plug with the back ow check valve attached thereto, is assembled on the derrick ioor before the head is attached to the string of casing which has already been run into the hole.

Of course, before running the string of casing into the hole, prior to the cementing operation, the frangible float assembly 95 has been placed in the oat shoe 2 and is held therein by the shear screws 96. This ioat assembly allows for the floating of the string of casing progressively into the hole.

The stall collar 3 is also placed at the desired point in the string of casing.

The ball 23 may be placed within the receptacle l2 by removing the cap 24 and placing the ball in the receptacle against the rounded head 32 on the handle I3; or it may be placed in the receptacle by pushing it upward through the bottom of the cementing head before it is positioned on the casing and engaging it by the head 32 to hold it therein.

A primary plug 34 is hung in the cementing head 5 by threading the shaft 3S through eye 35 and inserting the head 31 in the receptacle 39 in the manner hereinbefore described; and the plug 48 with the back ow check valve 49 attached thereto is engaged to the cap 1 and the cap screwed into the top 'of the cementingvhead in the manner hereinbefore described.

Before positioning the primary and top plugs in the cementing head, the bores 12 therein are filled with fluid and stoppers 13 are inserted to close the bores to retain the fluid therein.

The cementing head is then placed on the upper end of the string of casing and held thereto by the collar 6.

It will be noted that the interior portion of the cementing head is smaller in diameter than the interior bore of the casing string I at the place where the cementing head 5 is joined onto the casing.

After the head 5 has been thus positioned on the casing, with the accessories therein, the valved inlet I8 is opened to allow the well mud to be pumped through the casing and up behind the casing to return to the surface storage facilities. After the well has Ibeen thus circulated satisfactorily to assure that there is an open well ow circuit, the trip ball 23 is released into the casing by disengaging the handle I3 and pulling it outward and thus allowing the trip ball to fall `by gravity into the casing bore. The trip ball is then pumped downward until it comes to rest in the valve seat |02 in the float assembly 95. Suflicient pressure is then applied thereto by the surface pumps to shear the screws 96 and eject the float assembly from the casing. A substantially free flowing casing bore is then provided for the pumping of fluids into the well flow circuit.

Further circulation is usually carried on through the well bore after the oat assembly is ejected from the lower end of the casing, before releasing the plug 34 into the well flow circuit.

At the desired time the plug 34 is disengaged in the head 5 by turningthe handle II counterclockwise and pulling it outward to release the eye 35 from the shaft 36 inthe manner hereinbefore described. v

After plug 34 has 'been thus released, the valved inlet I8, through which the well fluid has been pumped, is closed and another valved inlet I1 is opened to allow cementing slurry to be admitted into the cementing head and therethrough into the casing behind the primary plug 34.

The primary plug 34, being larger in outside diameter than the restricted opening I6 I, will be deformed and elongated in its pressured passage through such restricted opening, and in such process the stopper 13 is ejected from the lower end of the plug and theV fluid in the interior 12 thereof is partially expelled. The plug, while passing through the restricted opening IDI is made smaller in diameter than the interior diameter of the casing, and upon entering the casing will relax to the contours of the interior of the casing and the outer walls and lips of said plug will form tight frictional engagement with the inner walls of the casing.

Since the plug forms a tight frictional engagement with the inner walls of the casing and since it has the attributes of a solid, no fluid can by-pass it or pass through it, and thus the cementing slurry admitted behind it is perfectly segregated from the mud column ahead of it.

After the cementing slurry has been admitted into the casing, the plug 48, with the back flow check valve 49 attached thereto is released into the cementing head in the manner hereinbefore described.

The plug 48 is forced through the constricted opening IOI and reacts exactly the same Way that the plug 34 reacted when forced therethrough, and is admitted into the `casing carrying therewith the back pressure check valve 49.

The plug 48 acts both as a spacer plug to space the column of mud which follows it from the column of cementing slurry which precedes it, and as a conveyor` to carry the back flow check valve 49 to the place of seating in the stall collar.

After the plug 48 and back flow check valve 49 have been released from their locked position in the cementing head the cementing slurry conduit IT is closed and another of the valved conduits, entering the head, is opened to allow well mud to enter the head and therethrough to enter the casing.

The slurry, which is indicated by the numeral 91, and the well mud, indicated by 98, are then pumped downward in the casing and upward outside of the casing until the backilow check valve 49 comes to rest in the stall collar 3. The pumps are then stalled and the operator then knows that the cementing job has been completed. He then releases the pressure from the surface pumps and the backilow check valve 49 is prevented from moving upward in the casing by Virtue of the split ring 50 being engaged under the shoulder on the lower side of the inner tube I, and is prevented from moving downward because the upper side thereof is seated in the taper 54 provided on the upper end of the inner tube 5l.

During this procedure the plug 34 has been ejected into the bottom of the well bore 94.

The plug 34, the ball 23, the float assembly 95 and the stopper 13 are all made of material which may be penetrated and broken up by the drill bit should such ensuing procedure be required for bore hole deepening.

Any one of my plugs may be made and operated with perfectly straight side walls, having no lips, flanges, corrugations or other breaks,

It is to be understood that other and further modifications and forms of my invention may be devised and still remain within the spirit and scope of the appended claims.

I claim:

1. A fluid segregating plug comprising, a substantially cylindrical body of elastic material said plug having a central core portion, an outer wall, and a plurality of web members spaced about the end faces of the plug, said webs connecting the core and the outer wall, thereby forming a plurality of open recesses arranged through the end faces of the plug, the outer walls of said plug being adapted to conform to the inner surface of a conduit throughout the entire length of such walls.

2. A fluid segregating plug comp-rising, a cylindrical body made of elastic material and having an elongated outer face adapted to conform to the inner surface of a conduit, said plug having a hollow interior, said hollow interior being permanently closed at one end, and adapted to be closed at the other end by a removable member; a plurality of open compartments spaced about the upper end of the body; and a plurality of open compartments spaced about the lower end of the body.

3. A fluid segregating plug comprising, a cylindrical body made of elastic material, said body having an elongated outer face adapted to conform to the inner surface of a conduit, and

having a hollow interior portion; a connector member closing one end of said hollow interior portion, and the other end of said hollow interior portion being adapted to be closed by a removable member; a plurality of open compartments spaced about the upper end of the body; and a plurality of open compartments spaced about the lower end of the body.

4. A fluid segregating plug comprising, a cylindrical body made of elastic material with an elongated outer face thereon adapted to conform to the inner surface of a conduit, said plug having a hollow interior; a connector member closing one end thereof; and a removable member closing the other end thereof, the hollow interior confining a body of fluid; a plurality of open compartments spaced about the upper end of the body; and a plurality of open compartments spaced about the lower end of the body.

5. A fluid segregating plug comprising, a cylindrical body made of elastic material, said body having an elongated outer wall thereon adapted to conform to the inner surface of a conduit a central core portion; a plurality of webs spaced about the upper face of the plug, and connecting the core with the outer wall thereof, thereby forming a plurality of spaced intcrstices around the upper end of said cylindrical body; a plurality of webs spaced about the lower face of the plug, and connecting the core with outer wall thereof, thereby formingr a plurality of spaced intersticcs around the lower end of said body; and a partition separating said upper and lower interstices.

6. A fluid segregatng plug comprising, a cylindrical body made of elastic material having an elongated outer wall adapted to conform to the inner surface of a conduit; an inner cylindrical member centrally spaced from the said wall; a plurality of web members spaced about the upper and lower ends of said body and spacing said inner cylindrical member from said wall thereby forming a plurality of spaced compartments on the upper and lower ends of the plug; and a baille member extending between said inner cylindrical member and said wall, thereby forming a partition between the said upper and lower compartments.

'7. A fluid segregating plug comprising a cylindrical body made of elastic material; an elongated outer face provided on said body and adapted to conform to the inner surface of a conduit; an inner cylindrical member centrally spaced from the inner surface of said outer face; a series of webs peripherally spaced on the upper and lower ends of said cylindrical body, and spacing said inner cylindrical member from the inner side of said outer face; a baffle member extending around the inner cylindrical body and connecting same with the inner face of the said outer face of the said plug, and separating said upper and lower webs; a connector member attached to one end of said inner cylindrical body, whereby the said plug may be connected to another' member for the purpose of conveying said other member through a conduit.

8. A fluid segregating plug comprising, a cylindrical body made of elastic material; an elongated outer face on said body adapted to conform to the inner surface of a conduit; an inner cylindrical member centrally spaced from the inner side of said outer face; a series of webs on the upper and lower ends of said cylindrical body and spacing said inner cylindrical member from the inner surface of the said outer face; a baille member extending around the inner cylindrical body and connecting same with the inner side of the outer face of the said plug and also forming a partition between said upper and lower webs; a hollow interior being provided in said inner cylindrical portion, said hollow interior be- Hardcastle Mar. 12,;1935

Number Name Date Edwards Feb. 1, 1938 Wickersham July 11, 1939 Bald Jan. 9, 1940 Brown Oct. 7, 1941 Murray Mar. 24, 1942 Courter Mar. 24, 1942 Sandstone June 27, 1944 OLeary ;Mar. 4, 1947 Haynes et al Sept 6, 1949 Hall May 30, 1950 Lamb ,..J Nov. 7, 1950 Haynes June 3, 1952 

